Automatic metal measuring and feeding device



April 1946. w. H. SCHWARTZ ErAL 2,397,512

AUTOMATIC METAL MEASURING AND FEEDING DEVICE I N V EN TOR.S

WILLIAM H. SCHWARTZ 0nd NATHAN LESTER AT TORNEYS whim @01 April 1946- w. H. SCHWARTZ ETAL 2,397,512

AUTOMATIC METAL MEASURING AND FEEDING DEVICE Filed July 8, 1943 2 Sheets-Sheet 2 V :i INVENTORS WILLIAM H.SCHWARTZ and y NATHAN LESTER 63 62 Z ATTORNEYS Patented Apr. 2, 1946 AUTOMATIC METAL MEASURING AND FEEDING DEVICE William H. Schwartz and Nathan Lester, Cleveland, Ohio, assignors to Lester Engineering Company, Cleveland, Ohio, a corporation of Ohio Application July 8, 1943, Serial No. 493,860

14 Claims.

The present invention relates to a device for automatically extracting a desired quantity of molten metal from a bulk supply of same, such as from a meltingpot, and delivering the measured quantity to a point where it is to be cast or formed into the required shape. Heretofore, in the metal founding art, considerable difficulty has been encountered, particularly when operating under quantity production methods, in transmitting the individual molten metal charges from the main supply to the point where casting or solidification of such molten charge is to take place. The simplest expedient, of course, has been to use a ladle of known volume capacity and merely to dip or ladle the individual molten metal charges out of the melting pot, crucible or other molten metal bath container. Mechanical ladling devices for performing the same operation have also been known. Pneumatic pressure and vacuum systems also have been used for conveying charges of the molten metal from the melting pot.

However, all of these above generally outlined prior expedients have been subject to certain disadvantages, such as the spilling and splashing of the molten metal from the ladle, the solidification or freezing out of the metal in pneumatic pressure or vacuum lines, and the inability accurately to control within close limits the uniformity of the measured amounts of metal charges.

Our invention utilizes a vacuum lifting principle for educting the molten metal from the melting pot, together with an accurate and reliable control device for discontinuing the application of the vacuum when the desired amount has been withdrawn; and thus successfully overcomes the several disadvantages and difficulties heretofore encountered. Our invention also involves the operation of causing the molten metal to flow past a high point above the liquid level in the melting pot whereby the desired measured amount flows by gravity into a receiving chamber on one side of such high point and the excess metal flows in the other direction from the high point and back into the melting pot. This feature of our invention insures the complete and positive separation of the desired batch" of molten metal and prevents the inadvertent diminution of this segregated amount of metal after the vacuum lifting force becomes inoperative or is disconnected.

Our invention also provides a novel controlling device for rendering the metal lifting or pumping means inoperative, and wherein the molten metal itself cooperates as an element of an electrically actuated control circuit.

Additional objects and advantages of our invention shall become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

Fig. 1 is a partially diagrammatic view illustrating a device embodying the principle of our invention as applied to a pressure casting machine;

Fig. 2 is an enlarged, sectional view of a portion of the apparatus shown in Fig. 1; and

Fig, 3 is a view similar to Fig. 2 but showing a modified form of construction.

Now referring more particularly to the drawings, there are shown therein a main source of molten metal supply, such as the melting not I, having the eduction conduit 2 leading from a point substantially midway of its upper liquid level and bottom to the batch receivingchamber 3. The receiving chamber 3 is herewith illustrated as being mounted upon the frame of a pressure casting machine, the pertinent parts of which are generally indicated at 5. The chamber 3 is located immediately above the feed inlet into the pressure casting chamber 4 in which the plunger 6 is adapted to reciprocate. A die cavity 1 is formed between the separable die blocks 8 and 9 and constitutes the forming mold into which the withdrawn batches of molten metal from the melting pot I are ultimately transferred and solidified or cast.

The conduit 2 includes two upwardly inclined portions 2a and 2b which join at their highest point with the vertical riser I0. As will be seen from Fig. 2, this high point, indicated at P, is above the normal liquid level of the receiving chamber 3 and of the melting pot I.

Heating means, such as the electrical resistance coils I I and I2, are provided for the conduit portions 2a and 2b, respectively, and for the purpose of maintaining a temperature in th conduit 2 high enough to keep the metal therein in a molten condition. A heating coil as indicated at I3 is likewise provided for the chamber 3 and adjacent its internal, metal receiving cavity I4.

A discharge opening I5 is provided in the bottom of the cavity I4 and is adapted to be closed 20, slidably is mounted in the chamber 3 by means of the feed screw 22 which is held against rotation by means of the pin 23 engaging in the slot 24. The feed screw engages with the adjusting nut 25, so that rotation of the latter operates to move the feed 'screw and displacement cylinder 26 to the desired vertical position with respect to the interior of the cavity l4.

A pneumatic vacuum line 26 is connected to the cavity "I4 of the receiving chamber 3 as indicated at 21 and also connected at 28 to the closure cap 29 on the top of the riser II). An electric terminal plug 39 having the insulator portion 3| and the long depending electrode 32 is mounted in the top of the closure cap 29. As shown in Fig. 2, the electrode 32 extends down to the end of the riser III or to a point substantially coincident with the highest point of the inner surfaces of the conduit portions 2a and 2b. The vacuum line 26 leads to the control valve 33 which is in turn connected to the line 34 leading to the vacuum pump 35. The valve 33 is also connected to the exhaust port 36 leading to the atmosphere. The stem 31 of the valve 33 is loaded by the compression spring 36 so that it is normally in the position shown in Fig. 1 wherein the line 26 i connected to the line 34 to the vacuum pump 35. The other or lower end of the stem 31 is connected to the core of the electric solenoid indicated at 39.

In the construction shown in Fig. l, the -perating lever l8 of the gate I6 is connected by means of the rod 46 to the core of the electric solenoid 4|. A tension spring 42 urges the lever l8 toward closed position and against the movement of the solenoid 4|.

An electric circuit, deriving electric power from the lines L1 and L2, controls the operation of the above described apparatus, and the connections of such electric circuit are as follows:

The line L1 has one branch 43 grounded to the condr'it 2, such as indicated at 44. The branch 45 from the line L1 leads to the push button switch 46 to one of the terminals of the solenoid operated switch 41. Th line Lo has one branch 46 leading to the solenoid 39 which is in turn connected with the other terminal of the switch 41 by the line 49 and thence through the line 59 to the other terminal of the solenoid operated switch 41. The other branch from the line L2 leads to the winding 52 of the solenoid switch 41, then through the line 53 to the terminal of the mounting plug 3| of the electrode 32. The

line 53 is shunted across from one end of the solenoid 52 to terminal of switch 41 to which the line 49 is connected, as indicated at 54. The solenoid 4| is connected in parallel with the solenoid 39, viz: by the line 55 connected to the same terminal of the switch 41 as the line 49.

Th operation of the above described device and controlling circuit is as follows:

When the valve 33 is in the position as shown in Fig. 1, the vacuum pump 35 exhausts air from the cavity I4, the riser l9 and the conduit 2, thus causing molten metal from the melting pot to be pumped up through the conduit 2 and into the receiving chamber cavity |4. When the level of the molten metal reaches the point A as indicated in Fig. 2, the electrode 32 is grounded, thus closing the circuit between the lines 43 and 53. In other words, the molten metal in contact with the end of the electrode 32 acts as a fluid conducting medium which closes the electric gap formed by the spacing and insulation of the electrode 32 from the surrounding metal parts which decreased.

are connected or grounded to the line 43. As this electric gap is closed, current then flows through the lines 43 and 53 to the solenoid 52 to the line 5|, closing the terminals of the switch 41 and permitting current to flow from the line 'in the cavity l4 and in the conduit portion 2b.

Simultaneously with the actuation of the switch 41, current flows from the line 45, switches 46 and 41 through line 55, through solenoid 4| and thence through lines 59 and 5|, thus actuating solenoid 4!. The solenoid- 4| moves the operating lever l6 and gate l6 to open position, permitting the fluid metal from the cavity H to be discharged into the casting cylinder 4. The return flow of the excess molten metal through the conduit portion 2a is quite rapid, so that by the time the gate |6 actually uncovers the discharge opening l5, all the excess metal to the left of the high point P (Fig. 2) has drained back to the right thereof.

ton switch 46 is actuated, opening the circuit to the solenoids 4| and 39 and permitting the gate l6 to close and the valve 33 to be moved back to position where the vacuum line 26 is again connected to the vacuum pump 36, whereby,an-

other batch of metal is drawn into the receivin cavity l4.

cycle of operation is adjustably regulated by varying the position of thedisplacement cylinder 20. The lower the cylinder 26 is moved into the cavity M, the greater the volume capacity of the latter is decreased and the amount of withdrawn molten metal received therein is correspondingly It will thus be seen that a very accurate control of the amount of measuredmolten metal is obtainable The discontinuance of the pumping action of the vacuum line 26 is entirely automatic, reliable and foolproof. It will be seen that there is no opportunity for molten metal to be drawn into the vacuum line 26 where it might otherwise solidify and cause a stoppage thereof,

because as soon as the liquid level of the molten metal'reaches the contact making point A, the vacuum is discontinued. The distance between the end of the electrode 32 and the vacuum line connection 26, determined by the length of the riser l6, thus functions as a "safety or neutral zone" which prevents any molten metal from entering into the vacuum line system, even though there might be a flow surge or momentum tending to carry some of the metal slightly higher up into the riser l6 even after the vacuum is shut off or opened to atmosphere. The brief period in which excess molten metal from the conduit portions 2a and 2b flows back into the melting pot I also automatically compensates for any such excess surge of metal into the receiving cavity I4, so that the same amount of predetermined measured quantity will be left in the cavity |4 upon each cycle or operation.

It will be apparent to those skilled in the art that equivalent means of forcing or pumping the molten metal from the melting not I through the To repeat the cycle of operations the push butreceiving chamber 6| and of the melting pot.

conduit 2 and into the receiving chamber 3 can be employed than the vacuum system herein specifically shown and described. We intend that such equivalent molten metal pumping means shall be included within the scope of our invention.

In the alternative form of construction shown in Fig. 3, the riser housing the electric gap electrode is assembled in place of the adjustable displacement cylinders 20. Thus, in Fig. 3, the conduit 60 leads from the meltin pot and has a high point alcove the normal liquid levels of the A discharge opening 62 together with the gate 63 is likewise provided for'the receiving chamber 6|.

The riser 64 threadedly engages with the adjusting nut 65 so that it can be moved to various vertical positions within the chamber 6 I. The upper end of the riser 64 is connected to a vacuum line 26' which in turn is connected to a control valve and electric actuating system similar to that previously shown and described in connection with Fig. 1.

The electrode 66 in the riser 64 projects to a point substantially in alignment with the bottom thereof. level of the molten metal within the chamber 6| reaches the bottom of the riser 64, the electrical contact is made across the electric gap formed by the electrode 66, thus shutting off the vacuum in the line 26 and the device then operated as previously described in connection with the form of construction shown in Figs. 1 and 2. Through the medium of the adjusting nut 65 the position of relative height through which the molten metal liquid level in the chamber 6| contacts the electrode 66 and thereby discontinues the vacuum pumping action determines the amount of metal received in the chamber 6|. That is, by lowering the riser 64 and shutting off the pumping action at a relatively earlier time, a smaller quantity of metal will be received in the chamber 6|; and conversely by raising the riser 64 and shutting off the pumping action at a, relatively later time, a greater quantity of metal will be received into the chamber 6 I.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employ-d.

We there ore particularly point out and distin otly claim as our invention:

1. A molten metal feeding device, comprising a molten metal re ervoir, eduction means connected to said reservoir. said means including a conduit having ascending and descending portions with a high point above the normal liquid level in said reservoir means for pumping molten metal from said reservoir through said eduction means,

As shown in Fig. 3, when the liquid electrically actuated means for controlling the operation of said pumping means, and a normally open electric circuit gap connected to said electrically actuated means, said gap being located in said eduction means at the highest horizontal level reached by the molten metal flowing therein and adapted to be bridged and electrically closed by molten metal contained therein, where by upon closing of the gap the pumping means is rendered inoperative.

2. A molten metal feeding device. comprising a molten metal reservoir, eduction means connected to said reservoir, said means including a conduit having ascending and descending portions with a high point above the normal liquid metal from reservoir through said eduction means, electrically actuated means for controlling the operation of said pumpingmeans, and molten metal contact means electrically connected to said electrically actuated means, said contact means being adapted to be actuated by contact with the molten metal pumped from said reservoir and located at a horizontal level above the normal flow level of molten metal in said eduction means whereby upon such contact of the molten metal, said pumping means is rendered inoperative.

3. A device for educting predetermined quantities of molten metal from a reservoir thereof. comprising an eduction conduit leading from said reservoir, means for forcing the molten metal from said reservoir through said conduit, electrically actuated means for controlling the operation of said forcing means, an electric circuit connected to said electrically actuated means, said conduit having ascending and descending portions with a high point above the normal liquid level in said reservoir and means for closing said electric circuit located at such high level point in said conduit and adapted to be closed by contact with the molten metal contained in said conduit, whereupon said means for forcing the molten metal is rendered inoperative.

4. A device for educting predetermined quantities of molten metal from a reservoir thereof, comprising a receiving chamber, an eduction conduit leading from said reservoir to said receiving chamber said conduit having ascending a d descending portions with a high point above the normal liquid level in said reservoir and chamber, means for pumping molten metal through said conduit, electrically actuated means for controlling the operation of said pumping means, an

electric circuit connected t said electrically actuated means, and molten metal contact means connected in said electric circuit, said contact means being adapted to be actuated by contact with the molten metal from said reservoir, thereby closing said electric circuit and rendering such pumping means inoperative said contact means being located at the highest horizontal level reached by the molten metal flowing in said conduit and in said chamber.

5. A molten metal feeding device, comprising a molten metal reservoir, a receiving chamber, a conduit leading from said reservoir to said receiving chamber said conduit having ascending and descending portions with a high point above the normal liquid level in said reservoir and chamber, suction means for lifting molten metal above such high point, and molten metal contact means for rendering said suction means inoperative when the liquid level in said receiving chamber reaches a predetermined height said contact means being located at substantially the same horizontal level as that of said high point.

6. A molten metal feeding device, comprising a molten metal reservoir, a receiving chamber, a conduit leadin from said reservoir to said receiving chamber said conduit having ascending and descending portions with a high point above the normal liquid level in said reservoir and chamber, suction means for drawing molten metal from said conduit and into said receiving chamber, electrically actuated means controlling the operation of said suction means, and a normally open electric circuit gap connected to said electrically actuated means whereupon said suction means is rendered inoperative, and adapted to be closed by contact with molten metal withdrawn level in said reservoir means for pumping molten 5' by said suction means said gap being located at a level corresponding t that of said high point.

7. A molten metal feeding device, comprising a molten metal reservoir, a receiving chamber, a conduit leading from said reservoir to said receiving chamber, said conduit having ascending and descending P rtions with a high-point above the normal liquid level in said reservoir and chamber suction means for drawing molten metal from said conduit and into said receiving chamber, electrically actuated means controlling the operation of said suction means, and spaced electric contact means connected to said electrically actuated means, said contact means being located at such high point in said conduit and adapted to be electrically bridged by molten metal drawn into said .conduit, whereupon said suction means is rendered inoperative.

8. A molten metal feeding device, comprising a molten metal reservoir, a receiving chamber, a conduit leading from said reservoir to said receiving chamber, said conduit having a high point above the liquid levels of said reservoir and of said receiving chamber, a vertical riser connected to said conduit at such high point, a pneumatic vacuum line'connected to the upper end of said riser, an electrode depending into t e interior of said riser and insulated and spaced therefrom, a solenoid actuated valve for rendering said vacuum lineiinoperative, and an electric actuating circuit connecting the solenoid of said valve to said electrode and said conduit, whereby the bridging of the space between-said electrode and said conduit by molten metal drawn into said conduit acts to close said circuit and operate said valve.

9. A molten metal feeding device, comprising a molten metal reservoir, a receiving chamber, a conduit leading from said reservoir to said receiving chamber, said conduit having a high point above the liquid levels of said reservoir and of said receiving chamber, suction means for lifting molten metal above such high point, molten metal contact means for rendering said suction means inoperative when the liquid level in said receiving chamber reaches a predetermined height, and

, means for varying the volume capacity of said retrically actuated means for simultaneously rendering said suction means inoperative and for opening said discharge gate, and a normally open electric circuit gap connected to said electrically actuated means and adapted to be closed by contact with molten metal withdrawn by said suc-,

' tion means.

11. A molten metal feeding device, comprising a molten metal reservoir, a receiving chamber, a conduit leading from said reservoir to said receiving chamber, said conduit having a high point above the liquid levels of said reservoir and of said receiving chamlier, suction means for drawing molten metal from said conduit and into said receiving chamber, a discharge gate located in the bottom of said receiving chamber, electrically actuated means for simultaneously rendering said suction means inoperative and for opening said discharge gate, a normally open electric circuit gap connected to said electrically actuated means and adapted to be closed by contact with molten metal withdrawn by said suction means. and means for varying the volume capacity of said receiving chamber.

' 12. A molten metal feeding device, comprising a molten metal reservoir, a receiving chamber, a conduit leading from said reservoir to said receiving chamber, said conduit having a high point above the liquid levels of said reservoir and of said receiving chamber, suction means for drawing molten metal from said conduit and into said receiving chamber, electrically actuated means controlling the operation of said suction means, spaced electric contact means connected to said electrically actuated means, said contact means being located at such high point in said conduit and adapted to be electrically bridged by molten metal drawn into said conduit, and means for varying the volume capacity of said receiving chamber. I

' 13. A molten metal feeding device, comprising a molten metal reservoir, 9. receiving chamber, a conduit leading from said reservoir to said receiving chamber. said conduit having a high point above the liquid levels of said reservoir and of said receiving chamber, a vertical riser connected to said conduit at such high point, a pneumatic vacuum line connected to the upperend of said riser, an electrode depending into the interior of said riser and insulated and spaced therefrom, a solenoid actuated valve for rendering said vacuum line inoperative, an electric actuating circuit connecting the solenoid of said valve to said electrode and said conduit, whereby the bridging of the space between said electrode and said conduit by molten metal drawn into said conduit acts to close said circuit and operate 'said valve, and 'means for varying the volume capacity of said receiving chamber.

14. A molten metal feeding device, comprising a molten metal reservoir, a receiving chamber, a conduit leading from said reservoir to said receiving chamber, said conduit having a high point above the liquid levels of said reservoir and said receiving chamber, a discharge gate located in the bottom of said receiving chamber,

a vertical riser connected to said conduit at such high point, a pneumatic vacuum line connected to the upper end of said riser and to the upper end of said receiving chamber, an electrode depending into the interior of said riser and spaced and insulated therefrom, a solenoid actuated valve for opening and closing said discharge gate, a second solenoid actuated-valve for rendering said vacuum line inoperative, and an electrically actuated circuit connecting the solenoids of both of said valves to said electrode and to said conduit, whereby the bridging of the space between said electrode and said conduit by molten metal drawn into said conduit acts to close said circuit and to operate said valves, thereby simultaneously rendering said vacuum line inoperative and opening said discharge gate.

WILLIAM H. SCHWARTZ. NATHAN LESTER. 

